This invention relates in general to astronautical educational devices and, in particular, to a system for demonstrating and explaining the phases of the moon to students.
Most students have a rudimentary knowledge of the various phases of the moon but do not understand what causes these phases. They are familiar with the terms xe2x80x9cfull moonxe2x80x9d, and xe2x80x9cnew moonxe2x80x9d but are unaware of the causes of the changes which causes the change in the moon""s appearance. A solely verbal explanation of the process of the moons various phases requires that the student have an understanding of the spacial and dynamic relationship of the earth and its sister planets with the sun and, more particularly, the relationship of the moon to these other celestial bodies. Such spatial relationships are difficult for many students to conceive and under stand, especially younger students.
Large planetary demonstration systems which can illustrate the sun-earth-moon interactions are available. However, they are expensive to build and operate and therefore are not readily available to all students. What is needed is a small portable inexpensive demonstrator which can be readily available and affordable in all classrooms.
The present invention described herein overcomes these disadvantages bay providing an uncomplicated, inexpensive astronautical demonstrator for classroom use which can readily and visually explain and demonstrate the sun-earth-moon interactions which cause the familiar phases of the moon to appear to viewers on earth.
The system of this invention provides a large outer hollow sphere, the inside surface of which, represents the closed universe. Positioned in the center of this xe2x80x9cuniversexe2x80x9d is a smaller inner sphere which represents the moon as viewed from earth. On the equator of the larger sphere, there is provided a light source extending through the outer surface of the outer sphere for illuminating the inner sphere xe2x80x9cmoonxe2x80x9d on the side facing the light source which represents the sun in this system. Arranged around the equator of the outer sphere are a plurality of viewing stations which allow the user of the system to view the moon from different angles with respect to the position of the sun. Each viewing station provide the viewer with a view of a different phase of the moon because of the angular relationship of the viewing stations to the xe2x80x9csunxe2x80x9d light source.
A detailed description of the invention and its operation are set forth in the specification below.